Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• The quantum anomalous Hall (QAH) effect in magnetic topological insulators (TIs) is crucial for dissipationless electronic devices.
• Current QAH materials like Cr- or V-doped (Bi,Sb)2Te3 require extremely low temperatures (below 100 mK) for full quantization, limiting practical applications.

Purpose of the Study:

• To investigate the effect of magnetic codoping on the temperature at which the QAH effect can be achieved.
• To explore strategies for enhancing the operating temperature of QAH materials for broader technological use.

Main Methods:

• Codoping (Bi,Sb)2Te3 topological insulators with both Chromium (Cr) and Vanadium (V) magnetic elements.
• Systematic transport studies on films with varied Cr/V ratios to analyze magnetic properties and surface band structure.

Main Results:

• Achieved full quantization of the QAH effect at 300 mK, a significant increase from previous limits.
• Observed a zero-field Hall resistance of 0.97 h/e^2 at 1.5 K.
• Demonstrated that magnetic codoping enhances ferromagnetic homogeneity and modulates the surface band structure.

Conclusions:

• Magnetic codoping is an effective strategy for significantly increasing the operating temperature of the QAH effect in topological insulators.
• This advancement paves the way for practical applications of dissipationless quantum Hall edge states at higher temperatures.